This device relates generally to apparatuses that mechanically peel food products, such as vegetables, and more particularly to food product peelers that use a freely tumbling peel bed.
Vegetables and other food products have traditionally been peeled by hand, using a knife or other tool to remove the skin and any bruises or other blemishes in the surface. Manual peeling is time-consuming and the human peeler can be injured by any mistake. Industrial peeling of vegetables is commonly accomplished by machines that remove an outer layer of the vegetables using rotating cylindrical brushes, rollers, or other structures that rub against the vegetable's surfaces and remove matter. This action desirably removes the skin and most blemishes.
Some industrial peelers are referred to as “U-bed” or “J-bed” continuous peelers. This is because the brushes, rollers, or other cylindrical abrasive structures that rotate against the vegetables' surfaces are arranged substantially parallel and their axes, when viewed from one end, extend around a U-shaped or J-shaped curve. A peeler “bed” is formed by the shape of the collection of closely-spaced rolls that support the vegetables while peeling them. The produce may be placed in one end of the peel bed and removed from the opposite end. Alternatively the produce may be placed in the peel bed in a batch and the entire batch removed from the peeler at one time. In both scenarios, during the time that the produce is traversing the length of the peeler, or simply tumbling around in the peel bed, the produce encounters the abrasive surfaces sufficiently to accomplish the desired result.
The current technology of so-called U-bed or J-bed continuous peelers is divided into two distinct groups, which represent different styles of machines. The first group is characterized by products sold by Vanmark Equipment, which use a peel bed made up of parallel abrasive rollers extending around a semicircle wrapping nearly 180 degrees, which means the rollers extend along the lowest portion of the peel bed and along both opposing sides of the peel bed in the shape of a half circle. When viewed from the end, the U-shaped or J-shaped curve that extends through the axles of the parallel rollers has a “diameter”, which is the distance between a first abrasive surface on one side of the curve and a second, opposing abrasive surface on the opposite side of the curve.
The overall motion in this style machine can be seen as a rolling product bed that is revolving roughly around an imaginary center of the peel bed diameter. The driving force for the motion is the abrasive surfaces on the peeler rolls. When this abrasive “traction” is high the group of product pieces moves in an ever-turning loop around the peel chamber's imaginary center, thereby exposing different product surfaces to the active peeling roll surfaces. The peel bed diameter, when viewed end on, is of a sufficient dimension that a product piece falling from the top-most part of the path will fall and be driven by other falling pieces toward the entry point sufficiently far that each will be reintroduced to the peeling action. This cyclical motion provides a random circulation of pieces toward and away from the abrasive surfaces.
In the case of continuous peelers, the motion of product longitudinally from the entry end to the exit end of the peel bed is driven by something akin to hydraulic leveling, because the combination of moving food product pieces, water and peel has fluid properties. The motion of the bed could be said to be “fluidized” and is somewhat unpredictable, because while one food product piece may reside in the bed for one amount of time, another piece may be resident in the bed for a different amount of time. Depending on the presentation of any given piece of product to the abrasive rolls the peeling effect may also exhibit similar variability. A constant infeed stream produces an equally constant exit stream similar to the water in a reservoir exiting over a dam as a result of forces caused by water introduced at the infeed end of the reservoir. Thus, as new product is introduced at the entry end the surface level of the moving product bed is forced to rise. With that rise, the product closest to the exit end spills over a threshold and exits the machine, thereby maintaining a product level equilibrium.
The second style machine is typically, but not necessarily, characterized by a larger diameter product bed with rolls often covering a smaller portion of the arc of the diameter than in the first style. The sides of the product bed are not intentionally specified dimensionally to maintain the product tumbling motion described in the first style. Without the rolling bed motion there is no guarantee that product will turn randomly or that it will move with a desirable level of uniformity through the machine. To improve the movement of the pieces an auger is commonly introduced through the center of the machine, and the auger urges the product through the machine. The auger has the advantage of more precisely controlling the period of time the product stays in the machine even though the auger does not guarantee a particular dwell time within the peeler for each product piece. Thus, even with the auger, the pieces are only encouraged to move along the roll bed.
Because of the physical proximity of the auger's angled surfaces to the roll bed, the auger controls longitudinal movement by interfering with the random motion desired to present all surfaces to the peeling action of the machine. An auger presents a continuous surface area that bears against the food products, such as potatoes, and that contact prevents the food products from moving freely. Furthermore, an auger presents a central axle that represents a continuous barrier to free motion if the product bed depth seeks to be higher than the central axle. Both features of an auger inhibit the natural rolling of the fluid bed referred to above, and this limits the inherently thorough removal of skin and blemishes from all products. One desirable feature of an auger is the control of residency or dwell time of food products within the peeler. If the depth of the peel bed is higher than the axle or center of rotation of the auger, the desired control over the food product time within the peeler is lost as individual product pieces “spill over” the auger walls into another cavity.
To overcome the disadvantage of this second type of peeler, peelers may be built with the larger bed diameter described above in association with the first type of machine. One advantage of this hybrid-style peeler over the first type is that it can be scaled quite large. One disadvantage is that when the bed is not tumbling freely, the ability to peel all surfaces evenly may be sacrificed.
Prior art peelers operate either in batch processes—in which the peeler is filled, the peeler operates, and then is emptied entirely—or continuous processes—in which product flows in one end and out the opposite end, and in which an average dwell time is assumed for each product. Dwell time, which is the amount of time that a piece of food product dwells in a peeler, is an important factor, because it has an effect on how much of the food product's outer surface is abraded. In batch processing, the dwell time is known, but batch processing is known to lead to large variations in the amount of product in the processing stream. The dwell time is averaged for each food piece in prior art continuous process peelers, and this may lead to some products being over-peeled and others being under-peeled. Other factors, such as roll speed, bed depth (depth of the food products in the bed), and others, affect the level of peeling from a minimum of essentially cleaning to a maximum of removing more than all of the skin. Once these peel-impacting factors have been established to optimize the amount of peeling in a continuous operation, changing any of them will reduce optimization. That is because varying one factor alters the optimized operation.
Examples of prior art peelers may be found in U.S. Pat. Nos. 7,428,863; 7,197,978; 7,121,929 and 5,858,429, all to Wallace. The preceding patents are hereby incorporated by reference. With a batch or continuous process peeler, the only way to adjust for greater supply or demand from upstream or downstream equipment is to perform more or fewer batches or to speed up or slow down the continuous operation peeler. However, the batch machine requires manpower to operate and can only handle a predefined number of batches per unit time. Furthermore, continuous operation machines are not optimized when the speed, quantity of food products and other factors are altered. Therefore, the need exists for a peeler that overcomes the above-noted disadvantages.